5,10-dihydrophenarsazine esters



United States Patent 3,481,958 5,10-DIHYDROPHENARSAZINE ESTERS John P. Pellegrini, Jr., OHara Township, and Harold 0.

Strange, Penn Hills Township, Allegheny County, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed Dec. 30, 1965, Ser. No. 517,808 Int. Cl. C07d 105/06 US. Cl. 260-404 9 Claims ABSTRACT OF THE DISCLOSURE Phenarsazine compounds useful as fungicides are represented by the general formula l OCORII! Preferred compounds are those wherein R and R are hydrogen and R is selected from the group consisting of alkyl and alkenyl radicals containing 3 to 9 carbon atoms, phenyl, hydroxyphenyl, alkylphenyl and phenalkyl radicals the alkyl portions of said alkylpheny and phenalkyl radicals containing 1 or 2 carbon atoms. Especially preferred is 5,10-dihydrophenarsazine-10-isooctanoate.

This invention relates to a method for controlling soildwelling fungi, and more particularly to novel phenarsazine compounds which are useful as fungicides to control soil-dwelling fungi.

Fungi are low forms of plant life which, lacking chlorophyll and being incapable of manufacturing their own food, live off other plants or animals. Thus, fungi are parasitic organisms many of which inhabit the soil and subsist on other living plants. If allowed to go unmolested, soil fungi can cause seed rot, injure plant roots and other underground parts of desirable plants and, in general, interfere with healthy plant development. When fungi invade a plant and become established therein, the plant is regarded as being diseased.

Fungi which cause seed rot include Phythi'um aphanidermatum, Fusarium culmorum and Rhizoctom'a solani. These fungi live in most agricultural soils since they compete successfully for space with other soil saprophytes. They are stimulated in growth by organic matter around germinating seed. If seed germination or seedling development is delayed by excessive moisture or low temperatures, the fungi may invade the seed or surround the young shoot before the plant can properly be established.

Various methods of combatting fungi that inhabit the soil have been employed, but the control of fungi is a problem that has not been entirely solved. Crop rotation, the elimination of weeds that may serve as hosts for disease organisms and the planting of resistant seed varieties has met with some success in reducing crop loss;fron1 fungi, but these methods have not been completely satisfactory. Seed coatings have been used to prevent seed decay and to protect seedlings near the seed ball, but the protection offered by seed coatings diminishes rapidly as the roots and young shoots extend beyond the immediate area of the seed. Soil fumigation has been used to reduce plant disease; however, the degree of success with soil fumigation is dependent upon many variables including the texture of the soil, the moisture content of thesoil, the temperature of the soil and the uniformity of the fumigation. In addition to these exacting conditions required with soil fumigation, fumigants are frequently toxic to desirable plants and thus should be substantially diffused from the soil prior to planting the desired plants.

We have discovered a group of phenarsazine compounds that are particularly useful as fungicides when incorporated in a fungi-infested soil. Thus, there are provided by this invention novel phenarsazine compounds, a fungicidal composition comprising said novel phenarsazine compounds, seed coated with said phenarsazine compounds, a method for controlling soil-dwelling fungi which comprises impregnating soil with said phenarsazine compounds as well as soil treated with said phenarsazine compounds.

The phenarsazine compounds of this invention have the following general formula:

OCOR

wherein R is a substituent selected from the group consisting of hydrogen, alkyl radicals containing from 1 to 4 carbon atoms and RCO-- radicals; R is selected from the group consisting of alkyl radicals containing from 1 to 7 carbon atoms and phenyl radicals; R" is selected from the group consisting of hydrogen and alkyl radicals containing from 1 to 12 carbon atoms; and R' is selected from the group consisting of alkyl and alkylene radicals containing from 2 to 11 carbon atoms and phenyl, hydroxyphenyl, alkylphenyl, alkoxyphenyl, phenalkyl, phenoxyalkyl and alkylphenoxyalkyl radicals wherein the alkyl portions of said alkylphenyl, alkoxyphenyl, phenalkyl, phenoxyalkyl and alkylphenoxyalkyl radicals contain from 1 to 12 carbon atoms. In the above formula, the R radicals can be alike or different. Examples of compounds having the above structural formula include 5, l O-dihydrophenarsazine-l O-propionate 5, IO-dihydrophenarsazine-10-propenoate 5, IO-dihydrophenarsazine- IO-butyrate 5,10-dihydrophenarsazine-IO-isobutyrate 5,10-dihydrophenarsazine-10-crotonate 5 1 O-dihydrophenarsazine-l O-valerate 5 1 O-dihydrophenarsazine- 10-isovalerate 5,10-dihydrophenarsazine-10-pivalate ,10-dihydrophenarsazine-10-[4-pentenoate] ,10-dihydrophenarsazine-lO-hexanoate IO-dihyd rophenarsazine-l O-isohexanoate IO-dihydrophenarsazine-10- [Z-hexenoate] 1 O-dihyd rophen arsazine- 1 O-octano ate ,10-dihydrophenarsazine-10-isooctanoate 1 O-dihydrophenars azine- 1 O-non-anoate.

5, IO-dihydrophenarsazine- 10- [p-n-hexylbenzoate] 5, 10-dihydrophenarsazine-10-[p-n-heptylbenzoate] 5 IO-dihydrophenarsazine- 10- p-isooctylbenzoate] 5, IO-dihydrophen-arsazine-10- [p-methoxybenzoate] 5 lO-dihydrophenarsazine- 10- p-ethoxybenzoate] 5 1 O-dihydrophenarsazine-lO- [p-isopropoxybenzoate] 5, lodihydrophenarsazine- 10- [p-n-butoxybenzoate] 5 l O-dihydrophenarsazine- 1 [-p-isoamyloxybenzo ate] 5, 1 O-dihydrophenarsazine-l 0- p-n-hexoxyb enzo ate] 5 IO-dihydrophenarsazine-IO- p-n-heptoxybenzoate] 5, IO-dihydrophenarsazine--[p-isooctoxybenzoate] 5,IO-dihydrophenarsazine-10-phenylacetate 5,10-dihydrophenarsazine-lfl-phenylisopropanoate 5,10-dihydrophenarsazine-IO-phenylbutyrate 5,10-dihydrophenarsazine-10-phenylisovalerate 5 1 O-dihydrophenarsazine-l O-phenylhexanoate 5,10-dihydrophenarsazine-10-phenylisooctanoate 5,10-dihydrophenarsazine-10-phenyldodecanoate 5 IO-dihydrophenarsazine-l O-phenoxyacetate 5,10-dihydrophenarsazine-IO-phenoxyisopropanoate 5 1 O-dihydrophenarsazine-IO-phenoxybutyrate 5,10-dihydrophenarsazine-10-pher1oxyisovalerate 5 l(J-dihydrophenarsazine-10-phenoxyhexanoate 5 l O-dihydrophenarsazine-10-phenoxyisooctanoate 5,lO-dihydrophenarsazine-10-phenoxydodecanoate 5, l 0-dihydrophenarsazine-IO-methylphenoxyacetate 5,10-dihydrophenarsazine-IO-methylphenoxyisopro-panoate 5,10-dihydrophenarsazine-lO-methylphenoxybutyrate.

5 1 O-dihydrophenarsazine-l O-methylphenoxyisovalerate 5,IO-dihydrophenarsazine-10-methylphenoxyhexanoate 5,10-dihydrophenarsazine-10-methylphenoxyisooctanoate 5,10-dihydrophenarsazine-10-methylphenoxydodecanoate 5 IO-dihydrophenarsazine- 1 O-ethylphenoxyacetate 5 1 O-dihydrophenarsazine-l O-n-propylphenoxyacetate 5 IO-dihydrophenarsazine-l O-n-butylphenoxyacetate 5,10-dihydrophenarsazine-10-isoamylphenoxyacetate 5, 1 O-dihydrophenarsazine- 1 O-n-hexylphcnoxyacetate 5, 10-dihydrophenarsazine-lO-n-heptylphenoxyacetate 5 1 O-dihydrophenarsazine-l O-isooctylphenoxyacetate 5,10-dihydrophenarsazine-lO-dodecylphenoxyacetate 5 IO-dihydrophenarsazine-5-metl1yl-0-butyrate 5, 1 O-dihydrophenarsazine-S-m ethyl- IO-isooctano ate 5,10-dihydrophenarsazine-S-methyl-10-isododecanoate 5, 10-dihydrophenarsazine-S-methyl-10-benzoate 5 l O-dihydrophenarsazine-S -methyl- 10-salicylate 5,10-dihydrophenarsazine-S-methyl-10- [p-toluate] 5,10-dihydrophenarsazine-S-methyl-10-[p-methoxybenzoate] 5,10-dihydrophenarsazine-S-methyl-10-pheny1acetate 5,lO-dihydrophenarsazine-S-methyl-10-phenoxyacetate 5,10-dihydrophenarsazine-S-methyl-l0-methylphenoxyisooctanoate 5 1 O-dihydrophenarsazine-S -ethyl-1 O-butyrate 5,10-dihydrophenarsazine-S-ethyl-10-isooctanoate 5 1 O-dihydrophenarsazine-S -ethyl-10-isododecanoate 5 10-dihydrophenarsazine-S-ethyl-10-benzoate 5 l O-dihydrophenarsazine-S -ethy1- l0-salicy1ate 5,10-dihydrophenarsazine-S-ethyl-10-[p-toluate] 5 10-dihydrophenarsazine-S-ethyl-1 0- [p-methoxybenzoate] 5 IO-dihydrophenarsazine-S -ethyl-1 0-phenyl acetate 5, 10-dihydrophenarsazine-S-ethyl- 1 O-phenoxyacetate 5 1 0-dihydrophenarsazine-5 -ethyl- 1 O-methylphenoxylsooct-anoate 5 1 O-dihydrophenarsazine-5-n-propy1-1 O-butyrate 5,10-dihydrophenarsazine-S-n-propyl-10-isooctanoate 5, lO-dihydrophenarsazine-S-n-propyl-10-isododecanoate 5,10-dihydrophenarsazine-S-n-propyl-IO-benzoate 5, l O-dihydrophenarsazine-S -n-propyl- 1 0-salicyl ate 5,10-dihydrophenarsazine-S-n-propyl-10- [p-toluate] 5, 1 O-dihydrophenarsazine-5-n-pr0py1-1 0- [p-rnethoxybenzoate] 5 1 O-dihydrO henarsa ine-S-n-propyl- 1 Q-phenyl acetate 4 5, 10-dihydrophenarsazine-S-mpropyl-10-phenoxyacetate 5 ,IO-dihydrophenarsazine-S -n-propyl-10-methylphenoxyisooctanoate 5 1 O-dihydrophenars azine-5-n-butyllO-butyrate 5,1O-dihydrophenarsaZine-S-n-butyl-IO-isooctanoate 5,10-dihydrophenarsazine-S-n-butyl-IO-isododecanoate 5,10-dihydrophenarsazine-5-n-butyl-10-benz0ate 5 10-dihydrophenarsazine-S-n-butyl-10-salicylate 5,10-dihydrophenarsazine-S-n-butyl-10- [p-toluate] 5,10-dihydrophenarsazine-S-n-butyl-10- [p-methoxybenzoate] 5,10-dihydrophenarsazine-S-n-butyl-10-phenylacetate 5 1 0-dihydrophenarsazine-S-n-butyl-1 O-phenoxyacetate 5 1 O-dihydrophenarsazine-S -n-buty1-lO-methylphenoxyisooctanoate 5 10-dihydrophenarsazine-5-acetyll O-isooctanoate 5, 1 O-dihydrophenarsazine-5-octanoyl-IO-isooctano ate. 5,10-dihydrophenarsazine-S-benzoyl-10-isooctanoate 5,10dihydrophenarsazine-Z-methyl-IO-isooctanoate 5 1 O-dihydrophenarsazine-Z,8-dimethyl-10-isooctanoate 5,1 O-dihydrophenarsazine-Z,S-diisooctyl-S-acetyl-IO- isooctanoate While all of the above phenarsazine compounds can be used as soil fungicides, it will be understood, of course, that their effectiveness may vary. Especially good results are obtained with phenarsazine compounds represented by the structural formula shown hereinabove wherein R andR" are hydrogen and R' is selected from the group consisting of alkyl and alkenyl radicals containing from from 3 to 9 carbon atoms, especially branched-chain alkyl radicals and phenyl, hydroxyphenyl, alkylphenyl and phenalkyl radicals wherein the alkyl portions of said alkylphenyl and phenalkyl radicals contain from 1 to 2 carbon atoms. Specific examples of compounds within the preferred group of phenarsazine compounds are:

5,lO-dihydrophenarsazine-lO-isobutyrate 5,IO-dihydrophenarsazine-10-crotonate 5,1Q-dihydrophenarsazine-IO-pivalate 5 1 O-dihydrophenarsazine- 10-0ctanoate 5 10-dihydrophenarsazine-IO-isooctanoate 5,10 dihydrophenarsazine-10-decanoate 5, IO-dihydrophenarsazine- 1 O-benzoate S, 1 O-dihydrophenarsazine-l 0-salicylate 5 ,10-dihydrophenarsazine-lO-[p-tOluate] 5, IO-dihydrophenarsazine- 1 O-phenylacetate The method of treating soil in order to control soildwelling fungi according to the invention comprises impregnating the soil with a fungicidal amount of the phenarsazine compound. This can be accomplished by applying the phenarsazine compound to the seed furrow as the seed is planted or by thoroughly mixing the phenarsazine compound with the soil prior to planting the seed. Other methods for applying the phenarsazine compound to the soil so as to impregnate the soil therewith includes the use of a diluent or carrier. Thus, for example, the phenarsazine compound can be admixed with an inert material such as talc, clay, diatomaceous earth, sawdust, calcium carbonate, and the like. The mixture is then incorporated into the soil. The phenarsazine compound can also be admixed with an inert liquid such as kerosene, acetone, benzene, toluene, xylene and the like in which the phenarsazine compound may be dissolved or dispersed. If desired, emulsifying agents and/or wetting agents can be used to obtain stable fungicidal compositions. Such solutions or dispersions can then be sprayed or otherwise applied to the soil. Also, in accordance with the invention, seeds can be coated with a fungicidal amount of the. phenarsazine compound.

The phenarsazine compounds according to the invention can be utilized in admixture with plant nutrients including compounds of calcium, magnesium, nitrogen, sulfur, phosphorus and potassium and with the socalled t ace e ements ma ganes iro zi c, copp nickel.

cobalt, boron, molybdenum and vanadium, if desired. In addition, the phenarsazine compounds can be applied in admixture with insecticides and other fungicides.

The amount of the phenarsazine compound employed to control fungi in soil infested therewith will depend upon a number of factors including the extent of the infestation, the uniformity of the application and the particular phenarsazine compound employed. In general, suitable rates of application to the soil to control soil-dwelling fungi are about 2 to about 200 pounds of the phenarsazine compound per acre of ground. Preferably an application rate of about 3 to about 40 pounds per acre is used. In any event, the amount of the phenarsazine compound applied to the soil is a small amount sufficient to control fungi dwelling in the soil.

The phenarsazine compounds of the preesnt invention can be prepared by reacting a phenarsazine-lO-oxide having the structural formula wherein R and R" are as defined hereinabove with the appropria e carboxylic acid. The molecular ratio of the carboxylic acid to the phenarsazine oxide is preferably about 2 to 1, carboxylic acid to phenarsazine oxide, respectively. Thus, a phenarsazine-lO-oxide having the above structural formula can be reacted with acids selected from the group consisting of alkanoic, alkenoic, benzoic, hydroxybenzoic, alkylbenzoic, alkoxybenzoic, phenylalkanoic, henoxyalkanoic, alkylphenoxyalkanoic acids and the like, Examples of specific acids within this group include propionic, propenoic, butyric, isobutyric, crotonic, valeric, isovaleric, pivalic, 4-pentenoic caproic, isohexanoic, 2-hexenoic, 'heptanoic, caprylic, isoo'ctanoic, pelargonic, capric, decenoic, undecanoic, IO-undecenoic, lauric, dodecenoic, benzoic, salicylic, toluic, ethoxybenzoic, phenylacetic, phenylpropanoic, phenoxyacetic and methylphenoxyvaleric acids.

The reaction between the phenarsazine-lO-oxide and the carboxylic acid is preferably conducted at the reflux temperature of the reactants. The reaction is continued until no more water is formed. Upon completion of the reaction and preciptiation of the phenarsazine product, the product is filtered and dried. The phenarsazine product is soluble to various degrees in organic solvents huch as benzene, toluene, xylene, chloroform, dimethylsulfoxide and dimethylformamide.

Phenarsazine-lO-oxide can be prepared by known chemical procedure. For example, about equal parts by weight of diphenylamine, orthodichlorobenzene and arsenic trichloride can be boiled in a glass flask equipped with a reflux condenser. Upon cooling the reaction mass, a product comprising diphenylamine chlorarsine (Adamsite) is obtained. About equal molar portions of sodium hydroixde in water and diphenylamine chlorarsine in acetone are then admixed at about 50 C. to give a 50-50 acetone-water mixture whereupon a product comprising phenarsazine-lO-oxide is obtained. This product is filtered and dried. The phenarsazine-lO-oxide thus obtained melts at a temperature greater than about 350 C.

According to another embodiment, the phenarsazine compounds of the present invention can be prepared by refluxing a phenarsazine chloride with a sodium salt of the appropriate carboxylic acid. The synthesis of phenarsazine compounds of the invention will be demonstrated by the following specific illustrative examples.

EXAMPLE I (5, IO-dihydrophenarsazine-l0-isooctanoate) A mixture of 317 grams (2.2 moles) of isooctanoic acid and 500 grams (1.0 mole) of 10,l0-oxybis (5,10-dihydrophenarsazine) [phenarsazine-lO-oxide] dispersed in 2.5 liters of toluene was stirred and refluxed at about 110 C. in a flask connected to a reflux condenser by means of a Dean-Stark trap. The reaction was continued until all the water of reaction was collected in the trap. The dark brown solution which resulted was filtered and the toluene Percent by weight for 5,10-dihydr0phenarsazine-lO-isooctanoate Found Theoretical Carbon 60. 17 62. 30 Hydrogen- 6. 11 6. 23 Oxygen 8. 76 8. 31 Arsenic 20. 31 19. 47

EXAMPLE II (5,10-dihydrophenarsazine-IO-decanoate) A mixture of 7 grams (0.041 mole) of decanoic acid and 10.0 grams (0.02 mole) of 10,10'-oxybis (5,10-dihydrophenarsazine') dispersed in 500 milliliters of toluene was stirred and refluxed at about 110 C. in a flask connected to a reflux condenser by means of a Dean-Stark trap. The reaction was continued until all the Water of reaction was collected in the trap. The solution which resulted was filtered and concentrated under vacuum to a volume of about milliliters. Subsequent dilution of the concentrate with petroleum ether precipitated a crystalline product which melted at 7883 C. with decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5,10- dihydrophenarsazine-l0-decanoate.

Percent by weight for 5,10-dih vdrophenarsazine-10-decanoate EXAMPLE III (5,10-dihydrophenarsazine-10-octanate) A mixture of 7.2 grams (0.05 mole) of octanoic acid and 12.5 grams (0.025 mole) of 10,l0'-oxybis(5,l0-dihydrophenarsazine) dispersed in 500 milliliters of toluene was stirred and refluxed at about C. in a flask connected to a reflux condenser by means of a Dean-Stark trap. The reaction was continued until all the water of reaction was collected in the trap. The solution which resulted was filtered and concentrated under vacuum to a volume of about 100 milliliters. Subsequent dilution of the concentrate with petroleum ether precipitated a crystalline product which melted at l02104 C. With decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5,10-dihydrophenarsazine-l0-octanoate.

Percent by weight for Percent by weight for 5,10-dihydrophenarsa- 5,10-dihydrophenarzine-lO-octanoate sazinelO-crotonate Found Theoretical Found Calculated Carbon.... 61. 88 62. 30 5 Carbon 58. 15 58. 70 Hydrogen- 6. 12 6- 3 Hydrogen 4. 35 4. 28 Oxygen 8. 51 8- 31 Oxygen 9. 67 9. 78

EXAMPLE 1 EXAMPLE VII (5, lO-dihydrophenarsazine-lO-benzoate) 10 (5,1o-dihydrophenafsazine-lo-hflXanoatc) A mixture of 278 grams (1.0 mole) of 10-chloro-5,10- dihydrophenarsazine, 144 grams (1.0 mole) of sodium benzoate and 3 liters of toluene was stirred and refluxed in a flask at about 110 C. for 2 hours. The dark brown mixture which resulted was filtered while hot. Subsequent chilling of the filtrate precipitated a tan crystalline prodduct which melted at 2046 C. with decomposition. Elemental analysis of the product shows it to compare favor- EXAMPLE V (5,10-dihydrophenarsazine-10-valerate) A mixture of 10.2 grams (0.1 mole) of Valerie acid and 12.5 grams (0.25 mole) of l0,10-oxybis(5,10-dihydrophenarsazine) in 500 milliliters of chloroform was stirred and refluxed at about 60 C. in a flask equipped with a modified Dean-Stark trap to collect the water formed in the reaction. The reaction was continued until no more water was collected. The light brown solution which resulted was filtered and concentrated under vacuum to a volume of about 100 milliliters. Subsequent dilution of the concentrate with petroleum ether precipitated a tan crystalline product. The product melted at 128-30 C. with decomposition. Elemental analysis of the tan crystalline product shows it to compare favorably with the theoretical analysis of 5,l-dihydrophenarsazine-l0- valerate.

Percent by weight for 5,10dihydrophenarsazine-IO-valerate Found Theoretical Carbon 59. 64 59. 45 4. 78 5. 25

In the following examples, the compounds were prepared in 500 milliliters of chloroform according to the general procedure described in Example V. After concentration of the filtrate under vacuum, the product either precipitated or was caused to precipitate by dilution with petroleum ether.

EXAMPLE VI ,10-dihydrophenarsazine--crotonate) 5,10-dihydrophenarsazine-10-crotonate was prepared by refluxing a mixture of 5.16 grams (0.06 mole) of crotonic acid and 15.0 grams (0.03 mole) of 10,10-oxybis(5,10- dihydrophenarsazine) in 500 milliliters of chloroform. The product melted at 232-234 C. with decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5,10-dihydrophenarsazine-l0-crotonat6.

5,10-dihydrophenarsazine-IO-hexonate was prepared by refluxing a mixture of 11.6 grames (0.1 mole) of hexanoic acid and 12.5 grams (0.025 mole) of 10,10-oxybis- (5,IO-dihydrophenarsazine) in 500 millimeters of chloroform. The product melted at 151-153 C. with decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5,10- dihydrophenarsazine-10-hexanoate.

5,10-dihydrophenarsazine 10 [IO-undeoenoate] was prepared by refluxing a mixture of 18.4 grams (0.1 mole) of 10-undecenoic acid and 12.5 grams (0.025 mole) or 10,10 oxybis(5,10 dihydrophenarsazine) in 500 milli. liters of chloroform. The product melted at 68-71 C. with decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5,10-dihydrophenarsazined0-[IO-undecenoate].

Percent by weight for 5,10-dlhydrophenararsazine-10-[l0- undeoenoate] Found Calculated Oarbmn 64. 56 65. 00 Hydrogen. 6. 64 6. 59 Oxygen 7. 20 7. 63

EXAMPLE IX (5,10-dihydrophenarsazine-10- [p-toluate] 5,10-dihydrophenarsazine-10-[p-toluate] was prepared by refluxing a mixture of 8.11 grams (0.06 mole) of ptoluic acid and 15.0 grams (0.03 mole) of 10,10'oxybis- (5,10-dihydnophenarsazine) in 500 milliliters of chloroform. The product melted at 174-176 C. with decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5,10- dihydrophenarsazine-IO- [p-toluate] Percent by weight for 6,10-dihydrophenarsazine-lO-[lO-[psazine-lO-[p-toluate] Carbon Hydrogen O xymm EXAMPLE X (5,10-dihydrophenarsazine-IO-phenylacetate) 5,10-dihydrophenarsazine-10-phenylacetate was prepared by refluxing a mixture of 8.2 grams (0.06 mole) of phenylacetic acid and 15.0 grams (0.03 mole) of 10,10- oxybis(5,IO-dihydrophenarsazine) in 500 milliliters of chloroform. The pr duc melted at 179-180 C. with decomposition. Elemental analysis of the product shows it to compare favorably with the theoretical analysis of 5, l-dihydrophenarsazine-10-phenylacetate.

Percent by weight for 5,10-dihydrophenarsazine-lO-phenylacetate Found Calculated Carbon.. 63. 03 63. 70 Hydrogen 4. 26 4. 24 Oxygen 8. 69 8. 49

EXAMPLE XI (5,10-dihydrophenarsazine-lO-phenoxyacetate) 5,10-dihydrophenarsazine-lO-phenoxyacetate was prepared by refluxing a mixture of 9.2 grams (0.06 mole) of phenoxyacetate acid and 15.0 grams (0.03 mole) of 10,10 oxybis(5,10 dihydrophenarsazine) in 500 milliliters of chloroform. The product melted at 190-192" C. with decomposition. Elemental analysis of the product in the number in the numerator is the healthy plant survival rating (fungus control) and the number in the denominator is the phytotoxicity rating. The schedule for rating the plants is as follows:

Healthy plant survival rating (both cartons) The results of the fungicidal tests with the representative phenarsazine compounds are recorded in Table I.

TABLE I.-FUNGICIDAL ACTIVITY OF PHENARSAZINE COMPOUNDS AGAINST PYTHIUM ROOT-ROTTING ORGANISMS OF PEAS Compound Rating at Pounds Per Acre of 5, IO-dihydrophenarsazine-IO-propionate- 5,10-d hydrophenarsazine-lO-butyrate 5,10-dihydrophenarsazine-lO-crotonate 5,10-dihydrophenarsazine-10-valerate 5,10-dihydrophenarsazine-lO-pivalate- 5,10-d hydrophenarsaZi ne-lO-hexanoate 5,10-dlhydrophenarsazine-lfl-octanoate 5,10-dlhydrophenarsazine-lO-isooctanoate.. 5,10-dihyd.rophenarsazine-lO-decanoate 5,10-d hydrophenarsazine-10-[IO-undecenoate] 5,IO-drhydrophenarsazine-IO-b enzoate 5, lO-d hydrophenarsazine-l0-salicylate 5,10-d hydrophenarsazine-l 0-[p-toluate].-- 5,10-d1hydrophenarsazine-lO-phenylacetate 4/4 Percent by weight for dihydrophenarsazine-10-phenoxyacetate Found Calculated Carbon. Hydrogen Oxygen Other phenarsazine compounds of the invention can be similarly prepared from a phenarsazine oxide and the approprite carboxylic acid or from a phonarsazine chloride and a sodium salt of the acid according to the procedure disclosed hereinabove.

In order to illustrate the utility of the phenarsazine compounds of the invention, representative compounds of the invention were tested as fugicides for controlling the soil-dwelling fungi, Pythium aphanidermatum. In making the fungicidal tests, 190 mg. of the phenarsazine compound are thoroughly mixed with 750 grams of dry sandy clay loam soil infested principally with Pythium aphanidermatum. This admixture corresponds to an application rate of 100 pounds of phenarsazine compound per acre. Additional tests are made at application rates of 50, 25, 12% and 6%. pounds per acre. The treated soil is divided into two portions which are placed in two 8-ounce waxed cardboard cartons. Five pea seeds are planted one-half inch deep in the soil in each carton. The cartons containing the planted peas are watered and incubated at 60 F. for 9 days. The planted peas are then examined and compared with peas planted in sterile soil an dincubated under the same conditions. The elfect of the tested compound on the planted peas is determined with respect to the number of healthy plants produced and also with respect to indications of phytotoxicity, i.e., indications of interference with germination or growth. The rating is written as a fraction where It is apparent from the data in Table I that the phenarsazine compounds cause no chemical injury of the plants, the phytotoxicity rating as shown in the denominator of the fraction being 4 in every instance. It is also evident that the phenarsazine compounds are effective fungicides in that a maximum survival rating was obtained in every instance at an application rate of pounds per acre. It will be noted further that the phenarsazine compounds for the most part are also elfective fungicides when used at lower application rates of 6% to 50 pounds per acre. While the valerate and hexanoate derivatives were not as effective at a rate of 6% pounds per acre as the other phenarsazine compounds, even these derivatives were quite effective at higher rates. Of the compounds listed in Table I, it will be noted that the crotonate, pivalate, octanoate, isooctanoate, decanoate, benzoate, salicylate, p-toluate and phenylacetate were extremely effective fungicides in that they had survival ratings of 3 or 4 even at an application rate of 6%. pounds per acre. The isooctanoate derivative of phenarsazine was an extraordinarily good fungicide as evidenced by its 4/4 rating at application rates of 6 A to 100 pounds per acre.

We claim: 1. A phenarsazine compound having the formula:

wherein R is selected from the group consisting of alkenyl and branched-chain alkyl radicals containing from 3 to 9 carbon atoms and phenyl, hydroxyphenyl, alkylphenyl and phenalkyl radicals wherein the alkyl portions of said alkylphcnyl and phenalkyl radicals contain from 1 to 2 carbon atoms.

. 5,10-dihydrophenarsazine-lO-isobutyratc.

. 5,10dihydrOphenarSaZine-10-crot0natc.

. 5,IO-dihydrophenarsazine-l0-pivalate.

. 5,IO-dihydrophenarsazine-lO-isooctanoate. 5,IO-dihydrophenarsazine-IO-benzoate.

. 5,10-dihydrophenarsazine-lO-salicylate.

. 5, 1 O-dihydrophenarsazine- 1 O-[p-toluate].

. 5,IO-dihydrophenarsazine-10-phenylacetate.

References Cited Chem. Abstracts: (1) Nagasawa et aL, Phenarsazinetype Agricultural Fungicides, 52, 10483i and 1048a; (2) Fukunaga et al., Bactericides for Agricultural Use, 54, 7056f.

ALEX MAZEL, Primary Examiner R. V. RUSH, Assistant Examiner US. Cl. X.R.

Patent No. 81,958 Dated December 2, 1969 Inventor) John P. Pellegrini, Jr. and Harold 0. Strange It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 31 "alkylene" should read alkenyl Column 3, line 42 O-" should read lO- Column 6, line 60 "octanate" should read octanoate Column 8, line 13 "grames" should read grams line 33 "or" should read of line 62 "lO-[lO-[p-sazine-lO-[p-toluate] should read lO-[p-toluate] Column 9, line "approprite' should read appropriate line 50 "phonarsazine" should read phenarsazine line "fugicides" should read fungicides line 68 F." should read F. 7

line "an dincubated" should read and incubated Column 12, line 2 "1048a" should read 10484a SIGNED AND SEALED MAY 2 6 1970 WILLIAM E. 'SCIHUYLER, JR- L- v Commissioner of Patents Aimer.

Edward M. Fletcher, I,

Attesting Officer 

